Water Activity

All forms of life depend on water. Water activity indicates the amount of water which is biologically available to microorganisms. It also affects a product’s texture, taste, colour, nutritional value and shelf life. Each species of microorganism (bacteria, yeast, mold…) has a minimum water activity value below which growth is no longer possible. 

Products

The measurement of the ‘free’ or available water in any product affects product quality and shelf-life. This is particularly crucial in the pharmaceutical, food and cosmetics industries which are highly regulated. If there is too much water in a product, there is a risk of microbial growth and water migration. This can lead to clumping, changes in consistency or taste, diminution of nutrients or effect product value, as well as reduced storage and shelf-life.

Measuring water activity makes it possible to monitor, control and optimize manufacturing and preservation processes ensuring physical, chemical and microbiological stability of moisture sensitive products.

We offer a wide range of instruments for the measurement of water activity (aw). These include handhelds, the laboratory analyzer HygroLab with four interchangeable probes, a PC-based instrument and the AwTherm with full sample temperature control. Small and large sample holders and liners are available for all product types including expensive medicinal liquids. A significant benefit is that no special product sample preparation is required making Rotronic analyzers easy to use after initial training. Our water activity analyzers can produce accurate and repeatable measurements of aw together with temperature in typically less than five minutes for most product samples, the equilibrium method is also available. Insertion probes can be used for bagged products.

Rotronic water activity probes can be calibrated and adjusted should this ever be necessary.